Leading shares are edging lower after Monday's gains, as investors await the outcome of the latest US Federal Reserve meeting.

The US central bank is widely expected to announced an easing of its $85bn a month bond buying programme, reflecting a recovering American economy. Economists expect a tapering of around $10bn, but the uncertainty has taken some of the shine off stock markets, which were boosted on Monday by news that the hawkish Larry Summers was quitting the race to succeed Ben Bernanke as Fed chairman. Mike van Dulken, head of research at Accendo Markets, said:

Markets are expecting tapering (consensus $10bn) and if anything we believe there now to be potential for a lower figure to be announced as a token gesture to maintain credibility in light of comments about improving economic picture. Maybe even more of a focus on revised forward guidance.

The FTSE 100 is currently 24.63 points lower at 6598.23, with miners turning in a mixed performance. Randgold Resources has recovered 57p to £45.43, but Glencore Xstrata is down 9.75p at 332.15p after UBS cut its recommendation from buy to neutral, citing pressure on copper and coal prices. The bank said:

While we are still attracted to Glencore Xstrata's refreshing strategy and improving free cash flow profile, we expect its valuation to cap performance until the outlook improves for copper/coal prices.

Severn Trent is leading the risers, up 41p at £17.99, wanted for its defensive qualities and also on vague bid talk.

After the government's sale of a 6% stake in Lloyds Banking Group, its shares have fallen 1.79p to 75.57p. Joe Rundle, head of trading at ETX Capital, said:

Many will see this as a symbol of the UK's financial system returning to health as institutional investors snapped up the shares on offer, an indication that the market feels far more comfortable with the UK banking sectors' prospects given the upswing we are seeing in the UK economy. Lloyds itself is a leveraged play on the UK economy for investors – if you believe in the UK recovery, Lloyds is the likely long play versus the likes of riskier banks RBS and Barclays.

Among the mid-caps, Debenhams has risen 2.6p to 105.8p after a positive trading update, saying the warm summer helped sales pick up in the fourth quarter. Full year like-for-like sales rose 2%, and the retailer said it expected to meet profit forecasts of around £153m for the 12 month period.

Pharmaceutical group BTG has dipped 1.6p to 377.4p after selling its brachytherapy business to Germany's Eckert & Ziegler for an initial $5m plus 30% of revenues for the next 12 months. Investec said:

With the product range already out of action since an FDA warning letter, we think management have taken the right action in disposing of the portfolio to focus BTG on higher priority growth projects, of which there are many. We expect this to have a minimal effect on forecasts and maintain our buy recommendation.